From 67fc53664a4f74f7a1b0327628c9e4c103824dd8 Mon Sep 17 00:00:00 2001
From: Michael Snoyman <michael@snoyman.com>
Date: Mon, 4 Mar 2013 09:18:05 +0200
Subject: [PATCH] Quote empty strings #24

---
 Data/Yaml.hs | 5 +++++
 test/main.hs | 2 ++
 2 files changed, 7 insertions(+)

diff --git a/Data/Yaml.hs b/Data/Yaml.hs
index b277294..6d69d48 100644
--- a/Data/Yaml.hs
+++ b/Data/Yaml.hs
@@ -114,6 +114,11 @@ objToEvents' (Array list) rest =
 objToEvents' (Object pairs) rest =
     EventMappingStart Nothing
   : foldr ($) (EventMappingEnd : rest) (map pairToEvents $ M.toList pairs)
+
+-- Empty strings need special handling to ensure they get quoted. This avoids:
+-- https://github.com/snoyberg/yaml/issues/24
+objToEvents' (String "") rest = EventScalar "" StrTag SingleQuoted Nothing : rest
+
 objToEvents' (String s) rest = EventScalar (encodeUtf8 s) StrTag PlainNoTag Nothing : rest
 objToEvents' Null rest = EventScalar "null" NullTag PlainNoTag Nothing : rest
 objToEvents' (Bool True) rest = EventScalar "true" BoolTag PlainNoTag Nothing : rest
diff --git a/test/main.hs b/test/main.hs
index 737bf53..c3b1391 100644
--- a/test/main.hs
+++ b/test/main.hs
@@ -241,7 +241,9 @@ sample = array
     [ D.String "foo"
     , object
         [ ("bar1", D.String "bar2")
+        , ("bar3", D.String "")
         ]
+    , D.String ""
     ]
 
 caseEncodeDecodeData :: Assertion